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김진호,조광래,임수정,이경자,경기천,엄미정,김희권,김찬용,이영한,이신찬,윤순강 한국환경농학회 2003 한국환경농학회지 Vol.22 No.4
This study was carried out to evaluate the status of the groundwater quality for paddy fields irrigation in Korea. Water samples were collected at 130 sites throughout the country. Samples were collected at three seasons-April, July and October-in 2000. According to our survey, the groundwater was found to be suitable for irrigation purpose. Average EC was shown 0.286 dS/m. Nitrate-nitrogen and Cl^(-) concentration was 5.6 ㎎/L, 32.95 ㎎/L which satisfied the Korean Standards for Irrigation Water. Nitrate-nitrogen concentration in each province was shown as following orders: Jeju (11.17 ㎎/L) > Chungnam (8.16 ㎎/L) > Gyeongbuk (6.64 ㎎/L) > Gyounggi (5.91 ㎎/L) > Chungnam (4.95 ㎎/L) > Gyeongnam (3.91 mgk) > Jeonbuk (3.50 ㎎/L) > Jeonnam (3.27 ㎎/L) > Gangwon (2.91 ㎎/L). The concentration by sampling seasons were October (6.62 ㎎/L) > July (5.88 mg&) > April (4.78㎎/L). As the soil of Jeju Province is usually derived from volcanic ash soils mainly used for upland drops, it may influence the nitrate-nitrogen concentration of groundwater. The amount of rainfall also influence the water quality. But the COD_(Cr), were shown April (3.17㎎/L) > July (2.91 ㎎/L) > October (2.40 ㎎/L), it is highly related in the basal dose of organic matter fertilizers. This study demonstrated that groundwater quality was suitable for irrigation, but continuous monitoring is recommended for agricultural policy and developing OECD agricultural environment indicators.
Simple current control without grid voltage sensor for traction solid-state transformer
Yun, Chun-Gi,Baek, Seunghoon,Bu, Hanyoung,Cho, Younghoon,Park, Jin-Hyuk,Kim, Myung-Yong The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.4
This paper proposes a simple current control method without a grid voltage sensor for a rectifier of traction solid-state transformer. The proposed control scheme estimates the phase angle of grid voltage from the fundamental frequency current of the grid. The extracted phase signal is normalized to generate a sinusoidal current reference by adopting a scaling factor to achieve a unity gain. Since the proposed control method operates without the grid voltage sensor for power factor correction (PFC), it offers a cost-effective solution with a simple implementation structure. However, this method cannot guarantee its control performance under weak grid conditions, where the frequency of grid voltage often varies. Thus, the control parameters of the proposed method are discussed and analyzed to minimize performance degradation. To verify the feasibility of the proposed control method, simulations and experiments are carried out on a 2 kW single-phase PFC converter. The proposed method provides as much control performance as the conventional method, which uses the grid voltage sensor.
이윤기 ( Lee Yun Gi ),임동진 ( Im Dong Jin ),윤희석 ( Yun Hui Seog ),김민호 ( Kim Min Ho ),김춘휴 ( Kim Chun Hyu ) 한국복합재료학회 2003 Composites research Vol.16 No.4
타이어 벨트층의 층간거동을 모사하기 위하여 2층 복합적층판을 고려하였다. 벨트층내의 층간전단응력 및 변형률을 결정하기위하여 3차원 유한요소해석을 수행하였다. 폭방향 전단변형률은 핀 이용법을 활용하여 측정되었다. 이들 실험 측정값은 적층판의 중앙부에서는 고전적층판이론과 그리고, 양가장자리부에서는 Kassapoglou 및 Kelsey의 이론과 비교하였다. 고무는 선형탄성체로 가정하였으며, 고무/코드 복합적층판은 직교이방성재질로 단순화 하였다. 해석결과로부터, 층간박리의 원인인 층간전단응력은 고무내부의 양가장자리부에서 가장 큰 값을 보였다. 결과값은 중앙영역에서 고전적 층판이론과 매우 잘 일치하였으며, 양가장자리부에서는 이론값들과는 다소 차이를 보였다. 2 ply laminated composite is regarded to simulate the interply behavior of the belt layer of the tire. It was done with 3 dimensional FE(Finite Element) analysis to determine interply shear stress and strain. Widthwise, the shear strain was measured by the pin method. These results are compared with those of CLT(c1assical lamination theory) in center region and those of Kassapoglou`s and Kelsey`s theory in edge region. In the FE analysis, rubber is assumed as linear elastic material, and rubbericord laminate as the orthotropic material composed of cord and rubber. In the FE result, interlaminar shear stress causing the interlaminar delamination has the largest value in the edge region of the inner rubber layer. Numerical results obtained coincides with CLT well in the center region. and agrees with other theoretical result little in the edge region.
Identification and Validation of Cryptochrome Inhibitors That Modulate the Molecular Circadian Clock
Chun, Sung Kook,Jang, Jaebong,Chung, Sooyoung,Yun, Hwayoung,Kim, Nam-Jung,Jung, Jong-Wha,Son, Gi Hoon,Suh, Young-Ger,Kim, Kyungjin American Chemical Society 2014 ACS CHEMICAL BIOLOGY Vol.9 No.3
<P>Circadian rhythms, biological oscillations with a period of about 24 h, are maintained by a genetically determined innate time-keeping system called the molecular circadian clockwork. Despite the physiological and clinical importance of the circadian clock, the development of small molecule modulators that directly target the core clock machinery has only been recently initiated. In the present study, we aimed to identify novel small molecule modulators influencing the molecular feedback loop of the circadian clock by applying our two-step cell-based screening strategy based on E-box-mediated transcriptional activity to test more than 1000 drug-like compounds. A derivative of 2-ethoxypropanoic acid designated as compound <B>15</B> was selected as the most promising candidate in terms of both efficacy and potency. We then performed pull-down assays with the biotinylated compound and find out that both cryptochrome (CRY)1 and 2 (CRY1/2), key negative components of the mammalian circadian clock, as molecular targets of compound <B>15</B>. In accordance with the binding property, compound <B>15</B> enhanced E-box-mediated transcription in a CRY1/2-dependent manner, and more importantly, it attenuated the circadian oscillation of Per2-Luc and Bmal1-dLuc activities in cultured fibroblasts, indicating that compound <B>15</B> can functionally inhibit the effects of CRY1/2 in the molecular circadian clockwork. In conclusion, the present study describes the first novel chemical inhibitor of CRY1/2 that inhibits the repressive function of CRY1/2, thereby activating CLOCK-BMAL1-evoked E-box-mediated transcription. Further optimizations and subsequent functional studies of this compound may lead to development of efficient therapeutic strategies for a variety of physiological and metabolic disorders with circadian natures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/acbcct/2014/acbcct.2014.9.issue-3/cb400752k/production/images/medium/cb-2013-00752k_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cb400752k'>ACS Electronic Supporting Info</A></P>
The Effects of Transcranial Direct-Current Stimulation on Cognition in Stroke Patients
Gi Jeong Yun,Min Ho Chun,Bo Ryun Kim 대한뇌졸중학회 2015 Journal of stroke Vol.17 No.3
Background and Purpose To investigate whether transcranial direct-current stimulation (tDCS) can improve cognition in stroke patients. Methods Forty-five stroke patients (20 males and 25 females, average age: 62.7 years) with cognitive dysfunction were included in this prospective, double-blinded, randomized case–control study. All patients were right-handed and the mean elapsed time after stroke was 39.3 days. Three different treatments groups were used: (1) anodal stimulation of the left anterior temporal lobe, (2) anodal stimulation of the right anterior temporal lobe, and (3) sham stimulation. tDCS was delivered for 30 minutes at 2 mA with 25 cm2 electrodes, five times/week, for a total of 3 weeks, using a Phoresor II Auto Model PM 850 (IOMED®). The evaluation of cognitive impairment was based on a Computerized Neuropsychological Test (CNT), Korean Mini-Mental State Examination (K-MMSE). The Korean version of the Modified Barthel Index (K-MBI) was used to assess activities of daily living functionality. These evaluations were conducted in all patients before and after treatment. Results Each group included 15 patients. Pre-treatment evaluation showed no significant differences between the three groups for any of the parameters. There was significant improvement in the verbal learning test on the CNT in the left anodal stimulation group (P<0.05). There were, however, no significant differences in the K-MMSE or K-MBI scores among the three groups. Conclusions These results demonstrated the beneficial effects of anodal tDCS on memory function. Thus, tDCS can successfully be used as a treatment modality for patients with cognitive dysfunction after stroke.
Gi Jeong Yun,Min Ho Chun,Ji Young Park,Bo Ryun Kim 대한재활의학회 2011 Annals of Rehabilitation Medicine Vol.35 No.3
Objective To investigate the synergic eff ects of mirror therapy and neuromuscular electrical stimulation (NMES)for hand function in stroke patients. Method Sixty patients with hemiparesis after stroke were included (41 males and 19 females, average age 63.3years). Twenty patients had NMES applied and simultaneously underwent mirror therapy. Twenty patients had NMES applied only, and twenty patients underwent mirror therapy only. Each treatment was done fi ve days per week, 30 minutes per day, for three weeks. NMES was applied on the surface of the extensor digitorum communis and extensor pollicis brevis for open-hand motion. Muscle tone, Fugl-Meyer assessment, and power of wrist and hand were evaluated before and after treatment. Results There were significant improvements in the Fugl-Meyer assessment score in the wrist, hand and coordination, as well as power of wrist and hand in all groups after treatment. Th e mirror and NMES group showed significant improvements in the Fugl-Meyer scores of hand, wrist, coordination and power of hand extension compared to the other groups. However, the power of hand fl exion, wrist fl exion, and wrist extension showed no signifi cant diff erences among the three groups. Muscle tone also showed no signifi cant diff erences in the three groups. Conclusion Our results showed that there is a synergic effect of mirror therapy and NMES on hand function. Therefore, a hand rehabilitation strategy combined with NMES and mirror therapy may be more helpful for improving hand function in stroke patients than NMES or mirror therapy only.